I also own a pair of Hippo VB's and found very little difference in bass using all of the bass ports. It was recommended to me to take all ports out and leave the backs 'empty', this actually sounds the best sound signature to my ears, you can try that.

Right now my soundmagic E10's beat the hippo vb's and are my preferred IEM, the hippo vb's are my backup IEM for when the e10's die, but i won't buy Hippo again, instead another IEM by Soundmagic (I find Soundmagic E10's to be incredible value for money).